1. Technical Field
The present invention relates to a rotor unit for a centrifugal separator for purifying flowing fluids, which rotor unit comprises a plurality of disk elements which are stacked concentrically one on another and provided with at least one centrally located fluid flow-through hole, where the disk elements have lead-through openings by means of which the disk elements are pushed onto essentially axially elongate guide elements distributed in the circumferential direction for guiding the disk elements in the circumferential direction and radially, and where the disk elements are held together by a first and a second end element at the ends of the stack of disk elements, at least some of the guide elements comprising tie rods which are arranged so as to interact with the end elements in such a way that the end elements can be displaced toward one another while the disk elements are pressed together, in addition to which means are arranged so as to engage in a locking way with the tie rods for retaining the disk elements in a pressed-together state with a small gap-forming interspace between the disk elements, the rotor unit being arranged so as to be rotated in a surrounding housing by a motor.
2. Background Art
In centrifugal separators of the abovementioned kind with axially long rotor units, problems of deflection of the central portions of the guide and tie rods can occur during operation as a result of the centrifugal forces acting on them. The deflections are proportional to the length of the rods raised to the fourth power and inversely proportional to the radius raised to the second power. Doubling the length of the rods therefore requires a fourfold greater diameter, which makes the rods 16 times heavier per unit length. In order to increase the flow capacity through the rotor unit, it is usual to increase the diameter of the fluid flow-through hole of the disk elements as well. By virtue of this, the rods have to be moved outward, which means that the centrifugal force on the rods, and thus the deflection problem, increases.